As one of the processes for producing dies used for cutting an adhesive tape such as a label or marker into a prescribed form, it is known to produce the dies having a prescribed cutting pattern (convex portion) by forming on a steel plate such as a low carbon steel or the like a resist so as to correspond to said cutting pattern, followed by etching treatment. This conventional process for producing dies as mentioned above, however, involves such problems that in some cases no edge having a good height is obtained or a cutting edge obtained is found dull.
With the view of solving such problems as mentioned above, there have been proposed die-producing processes relying on the two-step etching (Japanese Patent Publication No. 10000/1977 and 27938/1982, Japanese Patent L-0-P Publn. No. 105980/1988).
In the process for producing dies relying on the two-step etching, a resist corresponding to a cutting pattern is formed on a steel plate, the steel plate is subjected to etching treatment to form a convex portion corresponding to the cutting pattern, the resist remaining on the top of the convex portion is removed therefrom, and the steel plate thus treated is subjected again to etching treatment so that said convex portion is processed so as to have a sharp edge thereon.
In the prior art processes as mentioned above, the end portion of the resist (so-called burr) hangs down to cover the top of the convex portion with the progress of the etching treatment, and therefore the vicinity of the top of the convex portion is not etched and the center portion of the side of the convex portion is liable to etching (side etching). In a word, there were involved such problems that because of inequality of the side etching at the side of the convex portion which makes the center portion of said convex portion thinner, said convex portion will decrease in strength or will break.